Turning Movement Count (TMC): Methodology and Interpretation

1. Introduction

Turning Movement Count is one of the most critical traffic survey techniques used in transportation engineering to understand how vehicles pedestrians and cyclists move through intersections and junctions.
By measuring left turn right turn and through movements at conflict points TMC provides essential input for intersection design signal planning capacity analysis and safety assessment.
In modern Smart City and Highway ITMS projects turning movement counts form the foundation for efficient intersection control corridor optimization and adaptive signal operations.

2. What Is Turning Movement Count

A Turning Movement Count refers to the systematic measurement of traffic volumes by movement direction at an intersection or junction during a defined time period.
It records the number of vehicles pedestrians and cyclists making left turns right turns and through movements on each approach and lane group.
This data enables engineers to analyze traffic distribution conflict patterns saturation levels and operational performance at intersections.
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3. Objectives of Turning Movement Counts

Turning movement counts are conducted to achieve multiple planning design and operational objectives including:

• Measuring directional traffic distribution at intersections

• Identifying dominant turning flows and imbalanced approaches

• Supporting signal phase sequence and timing design

• Evaluating intersection capacity and level of service

• Assessing queue formation and approach delays

• Identifying conflict points and safety risks

• Supporting corridor coordination and progression planning

These objectives ensure safe balanced and efficient intersection operations.

4. Types of Turning Movement Counts

Turning movement counts may be conducted under different temporal and operational conditions depending on study requirements.

4.1 Peak Period Turning Movement Counts

Peak period TMC focuses on the highest demand periods of the day such as morning and evening peaks.
Applications include:

• Signal timing and phase split design

• Capacity and saturation flow analysis

• Congestion mitigation planning

• Intersection improvement feasibility studies

4.2 Off Peak and All Day Turning Movement Counts

These counts capture traffic movement patterns across non peak and full day periods to understand temporal variation.
Applications include:

• Time of day signal plans

• Corridor progression studies

• Background traffic analysis

• Access management evaluation

4.3 Pedestrian and Non Motorized Turning Counts

These counts include pedestrian crossings and cyclist movements at intersections.
Applications include:

• Pedestrian phase design and clearance time calculation

• School zone and campus planning

• Vulnerable road user safety assessment

• Complete street and multimodal design

5. Data Collection Methods for TMC

Turning movement counts are collected using manual video based and automated techniques depending on accuracy needs traffic complexity and survey duration.

5.1 Manual Turning Movement Counts

Manual TMC surveys are conducted by trained observers stationed at intersections or reviewing recorded footage.
They provide:

• High movement level accuracy

• Flexible classification of users and movements

• Visual observation of conflicts and behavior

• Reliable data for short duration detailed studies

Applications include signal design safety audits complex junction assessments and pilot studies.

5.2 Video Based Turning Movement Counts

Video based TMC uses roadside cameras with post processing or AI analytics to extract turning movements from recorded footage.
This method offers:

• Multi approach and multi lane movement classification

• Pedestrian and cyclist detection

• Replay and audit capability

• Reduced field manpower

• High accuracy in complex urban intersections

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5.3 Automated Turning Movement Counts

Automated TMC systems use AI based video analytics sensors and classifiers to continuously detect and classify turning movements in real time.
They provide:

• Continuous long duration movement monitoring

• Lane wise and approach wise classification

• High temporal resolution data

• Consistent and repeatable outputs

• Scalable deployment across multiple intersections

Futops ATCC – Traffic Counting and Classification supports automated turning movement detection and classification using AI analytics:
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This approach is increasingly used in Smart City deployments adaptive signal control systems and network wide intersection monitoring.

6. Survey Duration and Observation Periods

Turning movement counts are conducted over carefully selected time periods to capture representative demand and saturation conditions.
Common observation practices include:

• Peak hour and peak 15 minute intervals

• Morning and evening peak blocks

• 5 minute and 15 minute aggregation intervals

• Special event and school timing periods

• Full day intersection profiles

Proper selection of duration ensures accurate representation of directional demand queue formation and critical movements.

7. Data Processing and Output Parameters

TMC surveys generate several analytical outputs including:

• Turning volumes by approach movement and lane group

• Peak hour movement matrices

• Directional split ratios

• Movement based saturation flow inputs

• Queue length and delay indicators

• Pedestrian crossing volumes and clearance demand

These outputs form the basis for signal timing capacity evaluation and conflict analysis.

8. Interpretation of Turning Movement Data

Correct interpretation of TMC data is essential for effective intersection design and operation.
Key interpretation aspects include:

• Identification of dominant and critical turning movements

• Detection of unbalanced approach demand

• Analysis of left turn conflicts and protected phase needs

• Evaluation of right turn channelization requirements

• Assessment of pedestrian vehicle interaction

• Identification of spillback and blockage risks

These interpretations guide phase design lane allocation geometry modification and control strategy selection.

9. Applications of Turning Movement Counts

Turning movement counts are applied across a wide range of transportation engineering activities including:

• Signal phase sequence and timing design

• Intersection capacity and level of service analysis

• Roundabout feasibility and entry capacity design

• Channelization and lane configuration planning

• Corridor signal coordination

• Safety improvement and black spot analysis

• Pedestrian crossing facility design

These applications directly influence intersection throughput safety and operational reliability.

10. Role of TMC in Signal Design and Adaptive Control

Turning movement counts provide the primary input for:

• Phase split and green time calculation

• Cycle length determination

• Left turn phase justification

• Pedestrian clearance timing

• Transit and emergency priority planning

In adaptive signal control systems continuous turning movement data supports real time phase optimization demand responsive control and congestion mitigation.

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11. Integration with Traffic Management and ITS Platforms

Modern TMC systems integrate seamlessly with Traffic Management Systems and Intelligent Transportation Systems platforms.
This enables:

• Continuous intersection performance monitoring

• Real time congestion and queue detection

• Adaptive signal control inputs

• Corridor performance dashboards

• Safety analytics and operational reporting

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12. Benefits of Automated Turning Movement Counts

Automated TMC delivers multiple operational and planning advantages including:

• High accuracy in complex mixed traffic environments

• Continuous long term monitoring capability

• Reduced manpower and survey cost

• Faster data availability and processing

• Scalable city wide deployment

• Improved reliability of signal design and control

These benefits make automated TMC a core component of modern intersection intelligence platforms.

13. Future Trends in Turning Movement Analysis

Emerging trends include:

• AI based multi class turning detection

• Real time intersection performance dashboards

• Connected vehicle trajectory integration

• Video based conflict and near miss analytics

• Digital twin based intersection simulation

These innovations will further enhance intersection safety efficiency and adaptive control capability.

14. Conclusion

The Turning Movement Count methodology provides essential insight into directional demand conflict patterns and operational performance at intersections. By applying accurate counting methods advanced video analytics and automated systems transportation authorities can design safer more efficient and higher capacity intersections.
Futops delivers comprehensive Survey & Counting Systems Traffic Intelligence and Site Safety platforms designed to support Smart City and Highway ITMS turning movement analysis signal design and intersection planning initiatives.
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